Solar power collection system and methods thereof

ABSTRACT

Solar power collection systems characterized by using a collimated or otherwise concentrated beam of solar radiation to directly heat a porcelain or other high-heat capacity ceramic heating element by contact with an absorption surface on the element, which element in turn heats a thermal storage medium by conduction, methods of using the systems for collecting solar energy, and applications of the systems are disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.15/563,364, filed Sep. 29, 2017, which is the U.S. National Phase ofInternational Patent Application No. PCT/US2016/025481, filed Apr. 1,2016, which, in turn, claims priority to U.S. Provisional PatentApplication Ser. No. 62/141,488, filed Apr. 1, 2015. The disclosures ofall the applications are incorporated herein by reference in theirentirety.

FIELD OF THE INVENTION

This disclosure relates to solar power collection systems and methods ofusing the systems to collect solar power for consumptions.

BACKGROUND OF THE INVENTION

Concentrated solar power (CSP) collectors have been increasingly used inrecent times in conjunction with thermal storage media such as moltensalts in order to maximize the conversion of solar energy collected intousable mechanical work. For example salt-based thermal storage mediahave been used in large-scale solar-thermal power projects to extendpower output to periods when the sun is not shining. Existing solarcollectors use parabolic mirrors, dish shaped mirrors, Fresnel lenses,and other lens and mirror configurations to focus solar energy on flatpanel or evacuated tube collectors, which in turn provide heat to athermal storage medium or heat exchanger.

Evacuated tube and flat panel collectors usually work by using thecollected solar energy from parabolic, dish, flat panel or linearFresnel collectors to heat an absorption medium that then heats a heattransfer fluid such as molten salts or anti-freeze chemicals such aspropylene glycol, and this fluid is then used to heat a thermal storagemedium or to generate steam or other hot gases via a heat exchanger.While this approach accommodates high temperatures in the heat transferfluid, in the range of 300-400 degrees Celsius, the thermal storagemedia, often phase change materials such as nitrate salts and othermolten salt mixtures, can directly absorb much higher temperatureswithout boiling. However, most existing solar collectors such asparabolic or flat panel collectors are not configured to produce higherheating temperatures, and utilize heat transfer fluids to transfer heatto the thermal storage media, likely due to the difficulty of absorbingtemperatures that could damage existing flat panel or evacuated tubecollectors and to difficulties in pumping thermal storage media. Forexample, parabolic collectors focus the incident solar radiation acrossonly a single spatial dimension onto long evacuated tube collectors,resulting in radiative, convective, and other thermal losses across thelarge area of the collector surface. Projects using molten salts as heattransfer fluids also suffer from challenges resulting from the highfreezing temperature of the salt media and the resulting damage topiping system. Current projects that use solar radiation to directlyheat the thermal storage media at a central point of absorption, such assolar tower projects utilizing salt storage media, currently focus thesolar radiation via large heliostat mirrors, thus posing a danger topassersby and birds and losing a great deal of energy to reflection backinto the environment and to inefficiencies in mirror technology. Thismethod also suffers from so-called “cosine losses” resulting fromimperfect focusing of the solar radiation on the central absorber tower.

SUMMARY OF THE INVENTION

The present disclosure presents an alternative form of solar powercollection that utilizes a collimated or substantially collimated orotherwise substantially concentrated beam of solar radiation, forexample that produced by a Fresnel lens in conjunction with a convergingor diverging lens or by an appropriately shaped mirror surface, todirectly heat a porcelain or other high heat capacity ceramic heatingelement by contact of the beam with a concave or conical depression onthe element, which element may be placed in direct contact with or verynear a thermal storage medium, such as a phase change material, in a wayshown. The heating element transfers heat energy to the thermal storagemedium by conduction. Porcelain has been used for thousands of years dueto its toughness and extreme resilience to thermal stress. The resultingsolar absorbing device produces minimal reflection of the incident solarradiation into the environment, rendering it suitable for residentialuse.

In one aspect, the present invention provides a solar power collectingsystem, comprising: a means of forming a collimated beam of solarradiation; a heating element; and a thermal storage medium, wherein saidheating element can withstand heating from the collimated or otherwiseconcentrated beam of solar radiation without breaking; and wherein saidcollimated or otherwise concentrated beam directly heats said heatingelement through contact with a conical or concave depression on theelement; and wherein said heating element transfers solar energy to thethermal storage medium directly by conduction.

In another aspect, the present invention provides use of a solar powercollecting system according to any one of the embodiments describedherein, or any combinations thereof, for collecting solar energy.

In another aspect, the present invention provides a method of poweringan energy consumption apparatus, the method comprising collecting solarpower by using a solar power collecting system according to any one ofthe embodiments described herein, or any combination thereof, andpowering the energy consumption apparatus using the solar powercollected.

In one embodiment presented in this disclosure, a collimated beam ofelectromagnetic radiation is focused on the inside cavity of a conicalporcelain heating element, and its outside portion is submerged orembedded directly in the thermal storage medium. The outside portion ofthe element may optionally be protected from the storage medium by ametal sheath with high thermal conductivity. Beams produced by squaremeter Fresnel lenses can produce spot temperatures in excess of 500degrees Celsius on various material surfaces in environments withaverage sun insolation, which is in a range that porcelain and otherceramics can absorb without breaking, and which could produce moltensalt for heat storage.

Phase change materials with latent heats of fusion such as certainnitrate salt mixtures, e.g. so-called solar salt—a 60-40 mixture ofsodium nitrate and potassium nitrate—as well as other salt mixtures,such as those containing sodium sulfate and hydrates thereof, sodiumchloride, ammonium chloride, magnesium sulfate, other nitrate salts suchas calcium nitrate and hydrates thereof, sodium nitrate and potassiumnitrate, packed clays, and ceramic itself present good candidates forthe thermal storage medium.

The use of a Fresnel lens in conjunction with a converging or diverginglens to produce a collimated beam need make no use of focusing mirrors,though it may use mirrors to change the direction of the light beam, andthus loses minimal solar radiation energy to reflection back into thedevice's environment or to inefficiencies in the reflectivity of mirrorsurfaces. The solar collection cell presented in this disclosure isdesigned to absorb the resulting intense electromagnetic radiationwithout breaking and with minimal radiative losses, and in a way thatresults in high proportions of the absorbed energy being available foruse in various applications.

The thermal storage chamber formed by the solar collection methodpresented in this disclosure could be utilized for a number of usefulpurposes, such as the production of solar-thermal power in variousconfigurations, for example, for use as an evaporator for drivingorganic Rankine cycles for power generation, for water heating, snowmelting or the prevention of snow buildup, for the creation ofhigh-pressure steam to power engines, or to generate power through highpressure steam or other gases for powering a series of vortex tubesarrayed with Peltier thermoelectric generator elements, various culinaryapplications, and other uses of heat in human affairs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates collimated beam production with Fresnel lens andconverging or diverging lens.

FIG. 2A illustrates a ceramic heating element (the cross-section viewand top view) with conical or concave interior cavity.

FIG. 2B illustrates the ceramic heating element with two examples ofsurface textures to increase surface area.

FIG. 2C illustrates the ceramic heating element with nichrome wireattachments in vertical cross section and in top view with the lid ofthe storage capsule transparent.

FIG. 3 illustrates a ceramic heating element (the cross-section view andtop view) and thermal storage chamber indicating void for volume changeof a thermal storage medium.

FIG. 4 illustrates a setup of the solar power collection systemcontaining a refractory casing coupled with a boiler/evaporator system.

FIG. 5 illustrates a culinary application of the solar power collectionsystem.

FIG. 6 illustrates a setup of the solar power collection system as anevaporator for an Organic Rankine Cycle, showing the possible positionof an optional cooling/regeneration tank, and a trumpet-bell shapedmirrored chamber to redirect and collimate or otherwise concentrate thesolar radiation.

FIG. 7 illustrates an embodiment of the solar absorber with stagedchambers emanating away from the central heat absorption point andcontaining phase change materials with progressively lower meltingpoints.

FIG. 8 illustrates a vortex tube-Peltier series generator system.

DETAILED DESCRIPTION OF THE INVENTION

In one aspect, the present invention provides a solar power collectingsystem, comprising: a means of forming a collimated or otherwiseconcentrated beam of solar radiation; a heating element; and a thermalstorage medium, wherein said heating element can withstand heating fromthe collimated or otherwise concentrated beam of solar radiation withoutbreaking; and wherein said beam directly heats said heating elementthrough contact with a conical depression or concave surface on theelement; and wherein said heating element transfers solar energy in theform of thermal energy to the thermal storage medium by conduction.

In one embodiment of this aspect, the means of forming a collimated orotherwise concentrated beam of solar radiation comprises a Fresnel lensin conjunction with a converging or diverging lens.

In another embodiment of this aspect, the means of forming a collimatedbeam of solar radiation comprises a Fresnel lens whose focal point ispositioned at the top of a tube with reflective interior surface, thetop of which has a section that tapers to an opening into which thelight is focused, wherein the tapered portion is bent such that itresembles the bell of a trumpet aimed into the rest of the tube.

In another embodiment of this aspect, the heating element is placed indirect contact with the thermal storage medium to enable efficienttransfer of the heat energy from the heating element to the thermalstorage medium by conduction.

In another embodiment of this aspect, the heating element is separatedfrom the thermal storage medium by a metal sheath.

In another embodiment of this aspect, the heating element is of a shapecomprising a conical or concave interior cavity and an exterior wall sothat the collimated or otherwise concentrated beam of solar radiation isaimed at the interior cavity of the heating element.

In another embodiment of this aspect, the interior cavity of the heatingelement forms a cone or concave depression comprising angled walls thatmeet at a point at the bottom of the heating element's interior cavity;and wherein the diameter of the cone or concave depression is equal toor greater than the diameter of the collimated beam.

In another embodiment of this aspect, the angled walls of the heatingelement taper across the diameter of the collimated or otherwiseconcentrated beam, thus collecting the electromagnetic radiation fromthe beam across the height of the conical or concave interior cavity ofthe heating element.

In another embodiment of this aspect, the exterior wall of the heatingelement is placed in direct contact with the thermal storage medium.

In another embodiment of this aspect, the collimated or otherwiseconcentrated beam of electromagnetic radiation is focused on theinterior cavity of the heating element, and the exterior wall of theheating element is submerged or embedded directly in the thermal storagemedium.

In another embodiment of this aspect, the heating element is made of aceramic material.

In another embodiment of this aspect, the heating element is made ofvitrified porcelain with its surface of interior cavity optionallycoated by a layer of oxide-rich glaze in order to enhance absorption ofthe incident solar radiation and to act as a heat sealant.

In another embodiment of this aspect, the exterior surface of theheating element which is placed in contact with or faces the thermalstorage medium is textured to increase its surface area.

In another embodiment of this aspect, the texture of the surface that isplaced in contact with or faces the thermal storage medium is texturedwith a honeycomb pattern.

In another embodiment of this aspect, the surface of the heat absorberelement which is in contact with or faces the thermal storage medium isembedded with nichrome wires to increase thermal diffusivity.

In another embodiment of this aspect, the thermal storage mediumcomprises a mineral salt or mixture of salts capable of changing phaseto store the energy when absorbing the heat transferred from the heatingelement.

In another embodiment of this aspect, the thermal storage medium isselected from the group consisting of sodium sulfate and hydratesthereof, magnesium sulfate, ammonium chloride, sodium chloride,ceramics, nitrate salts such as calcium nitrate and hydrates thereof,potassium nitrate, and sodium nitrate, and mixtures thereof.

In another embodiment of this aspect, the thermal storage medium issodium chloride.

In another embodiment of this aspect, the thermal storage medium is a60-40 mixture of sodium nitrate and potassium nitrate.

In another embodiment of this aspect, the thermal storage medium iscoupled with an energy consumption apparatus through a heat transfermeans so that the heat energy stored in the thermal storage medium canbe used by the energy consumption apparatus.

In another embodiment of this aspect, the solar power collecting systemfurther comprises a solar tracking means to ensure a stationaryorientation of said collimated or otherwise concentrated beam of solarradiation in order to make optimal use of the solar insolationthroughout the day.

In another embodiment of this aspect, the solar power collecting systemis coupled with a solar tracking apparatus or a device producing acollimated or otherwise concentrated beam of solar radiation withstationary orientation as the sun light changes directions throughoutthe day.

In another embodiment of this aspect, the heating element is heated bythe collimated or otherwise concentrated beam of solar radiation focuseddirectly onto the heating element's concave or conical interior surface,while the exterior surface of the heating element is placed in directcontact with the thermal storage medium.

In another embodiment of this aspect, the heating element is shaped soas to avoid excessive thermal stress to it while heat transfer betweenthe heating element and the thermal storage medium is maximized.

In another embodiment of this aspect, the collimated or otherwiseconcentrated beam of solar radiation is produced using a Fresnel lens inconjunction with a converging lens or diverging lens as substantiallyshown in FIG. 1a or 1 b, respectively.

In another embodiment of this aspect, the thermal storage mediumsurrounds the heating element and is contained in a capsule made of aceramic, stainless steel, or another corrosion and heat resistantmaterial.

In another embodiment of this aspect, the heating element forms a lid ofthe capsule; and wherein optional ventilation holes or other shapedopenings are placed in the top or other areas of the heating element orin the capsule, or optional pressure valves are integrated, to allowrelease of pressure built up in the capsule.

In another embodiment of this aspect, the capsule comprises a sufficientempty space to accommodate volume change caused by phase change of thethermal storage medium.

In another embodiment of this aspect, the capsule is encased in arefractory material for added insulation, or partially surrounded by avacuum as in a Dewar tube.

In another embodiment of this aspect, the thermal storage medium forms athermal storage chamber stored underground or partially underground sothat the surrounding earth serves as insulation.

In some embodiments, the solar power collecting system comprises anarray of thermal storage chambers, wherein each interior chamber issurrounded by an outer chamber separated by a thermally conductivematerial, and each chamber holds a phase change material as thermalstorage medium.

In some embodiments, said array of thermal storage chambers comprisetwo, three, four, or five chambers; and wherein said phase changematerial in each outer chamber has a lower melting point than the phasechange material in the adjacent interior chamber.

In another embodiment of this aspect, the solar power collecting systemfurther comprises a thermally conducting tubing or finned tubing to bein contact with said thermal storage medium, so that a working fluid canpass through the tubing which in turn passes through the thermal storagechamber formed by the thermal storage medium and serves as a source ofheat energy to the working fluid.

In another embodiment of this aspect, the working fluid in said tubingacts as a boiler or evaporator to power an engine or turbine.

In another embodiment of this aspect, the tubing is made from a materialselected from stainless steel or ceramic.

In another embodiment of this aspect, the tubing or finned tubing isthreaded through larger extruded ceramic or thermally conductive plasticpipes that pass through the thermal storage medium, wherein optionally aplurality of pipes or finned tubes of a small diameter are used toensure rapid heat transfer from the thermal storage medium to theworking fluid.

In another embodiment of this aspect, the heating pipes coil around thetip of the heating element's exterior surface.

In another embodiment of this aspect, the working fluid is pumpedthrough a gravity-feed system into the heat cell to allow for optimalnet energy production.

In another embodiment of this aspect, a one-way valve is placed at theinlet to the thermal storage chamber to ensure the working fluid flowsonly towards the outlet.

In another embodiment of this aspect, the one-way valve comprises aTesla valvular conduit.

In another embodiment of this aspect, the gravity-feed or pump systemcomprises a feeding tank to feed the working fluid to the heatcell/boiler.

In another embodiment of this aspect, the feeding tank is placed in aclose proximity to the heat cell to enable recapture of the heat lostfrom the cell with the fluid or other medium contained in the tank. Thetank could also be used as a heat recuperator in an organic Rankinecycle.

In other embodiments, the present invention encompasses any and allreasonable combinations of the embodiments as substantially describedand shown herein.

In another aspect, the present invention provides use of a solar powercollecting system according to any one of the embodiments describedherein, or any combinations thereof, for collecting solar energy.

In another aspect, the present invention provides a method of poweringan energy consumption apparatus, the method comprising collecting solarpower by using a solar power collecting system according to any one ofthe embodiments described herein, or any combination thereof, andpowering the energy consumption apparatus using the solar powercollected.

In one embodiment, the energy consumption apparatus is an evaporator foran organic Rankine cycle.

In another embodiment, the energy consumption process is selected fromproduction of solar-thermal power, water heating, snow melting,prevention of snow buildup, the creation of high-pressure steam, powergeneration through high pressure steam; as an evaporator to heatrefrigerant fluids to power an Organic Rankine Cycle; and said energyconsumption apparatus is selected from power engines, hydraulic enginessuch as gerotor motors, steam engines, turbines, vortex tube coolers, aseries of vortex tubes arrayed with Peltier generators, culinaryapplications, and other uses of heat in human affairs.

In another embodiment, the thermal storage chamber is used as a boileror evaporator to power home steam turbines or steam engine basedgenerators, or organic rankine cycles using scroll or gerotor expanders,or to provide hot water and steam heat.

In another embodiment, the thermal storage chamber is used to heatcooking stones for use as cook surfaces, or to heat ovens.

In another embodiment, the cell is used as a cook surface after the cellis removed from the source of solar radiation.

In another embodiment, the thermal storage chamber produced by theheating element is used to generate steam or other heated vapors forpowering vortex tubes, which separate pressured gas into hot and coldstreams, which may be used for low-scale electricity generation usingPeltier generators operating on the Seebeck effect.

In another embodiment, the cold and hot ends of vortex tubes areoriented towards the cold and hot ends of a Peltier thermoelectricgenerator element, in a looped series.

In the following some more specific, non-limiting examples orembodiments are provided to further illustrate certain aspects of thepresent invention with reference to the Figures.

FIG. 1 illustrates an embodiment for collimated beam production withFresnel lens and converging or diverging lens, wherein 101 representssunbeams, 102 represents Fresnel a lens, 103 represents a diverginglens, 104 represents a converging lens, and 105 represents collimated orotherwise concentrated beams.

FIG. 2A illustrates an embodiment of a ceramic heating element (thecross-section view and top view) with conical or concave interiorcavity. In the cross-sectional view, 201 represents collimated orotherwise concentrated beams; 202 represents a ceramic heating element;203 represents a ventilation hole; 204 represents a salt storagereceptacle, which can be made of ceramic, stainless steel, or othermaterials; and 205 represents a salt medium. In the top view, 211represents ventilation hole.

FIG. 2B illustrates the ceramic heating element with two examples ofsurface textures (206 and 207) to increase surface area.

FIG. 2C illustrates an embodiment of the ceramic heating element withnichrome wire attachments in vertical cross section and in top view withthe lid of the storage capsule transparent (208—ceramic; 209—saltmedium; and 210—embedded nichrome wire).

FIG. 3 illustrates an embodiment of the ceramic heating element (thecross-section view and top view) and thermal storage chamber indicatingvoid for volume change of a thermal storage medium (in thecross-sectional view, 301—collimated beam, 302—void for volume change ofthermal storage; in the top view, 303—ventilation holes, 304—capsulelid).

FIG. 4 illustrates a setup of the solar power collection systemcontaining a refractory casing coupled with a boiler/evaporator system(401—valve, e.g, a Tesla one-way valve; 402—inlet of gravity feed orpump feed; 403—ceramic cell; 404—stainless steel casing; 405—refractorycasing; 406—collimated or otherwise concentrated beam; 407—outlet; and408—engine).

FIG. 5 illustrates a culinary application of the solar power collectionsystem (501—ceramic cell; 502—salt reservoir; 503—oxide surfacing(glaze); and 504—ceramic cell).

FIG. 6 illustrates a setup of the solar power collection system as anevaporator for an Organic Rankine Cycle, showing the possible positionof an optional cooling/regeneration tank, and a trumpet-bell shapedmirrored chamber to redirect and collimate or otherwise concentrate thesolar radiation (601—solar radiation; 602—“trumpet bell” reflector;603—liquid condenser medium; 604—reflective chamber; 605—pump; 606—checkvalve; 607—refractory casing; 608—metal casing; 609—salt medium;610—insulation; 611—condenser; 612—regenerative heat exchanger; and613—expander/generator).

FIG. 7 illustrates an embodiment of the solar absorber with stagedchambers emanating away from the central heat absorption point andcontaining phase change materials (PCM) with progressively lower meltingpoints (701—highest melting point PCM; 702—medium melting point PCM;703—lowest melting point PCM).

FIG. 8 illustrates a vortex tube-Peltier series generator system(801—steam inlet; 802—vortex tube; 803—hot outlet; 804—Peltierthermoelectric generator; 805—cold outlet).

In various embodiments, an apparatus and method is presented forcollecting solar radiation to heat a thermal storage medium with a highheat storage capacity such as a phase change material, e.g. solar salt,using a porcelain or other high heat capacity ceramic heating element(FIG. 2 and FIG. 3). The heating element 202 is heated by focusing acollimated or otherwise concentrated beam 201 of solar radiationdirectly onto a conical depression in or concave interior surface on theelement 202 (FIG. 2A) (or 403, FIG. 4) while the opposite side of theelement is placed in direct contact with the storage medium 205. Theelement 202 (FIG. 2A) (or 403, FIG. 4) is shaped to prevent excessivethermal stress to the element while maximizing heat transfer between theheating element and the thermal storage medium 205 by conduction. In oneembodiment, the element may be conically or spherically shaped 202 (FIG.2A) (or 403, FIG. 4), and the surface of the element which is in contactwith the thermal storage medium 205 (FIG. 2A) (or 609, FIG. 6) istextured 206-207 (FIG. 2B) to produce a high surface area to increaseheat absorption, for example in a honeycomb-like pattern 206 (FIG. 2B).In one embodiment, to prevent degradation, the porcelain absorberelement is separated from the thermal storage medium by a metal sheath,and the space between the sheath and the absorber element is filled witha protective material such as various clays. In another embodiment (FIG.2C), nichrome wire 210 can be fused directly to the portion of theabsorber element 208 exposed to or near the thermal storage medium 209in order to encourage thermal diffusion into the storage medium.

The collimated beam of solar radiation may be produced using a Fresnellens in conjunction with a converging lens 104 or diverging lens 105(FIG. 1A and FIG. 1B, respectively). This method makes optimal usage ofthe solar radiation entering an area of space. In one embodiment (FIG.6), the light could alternatively be collimated or substantiallycollimated by positioning a mirrored chamber 604 with the top portion inthe shape of a trumpet bell 602 as shown in FIG. 6, such that theopening of this chamber 602 was near the focal point of the Fresnellens. The bottom of the mirrored chamber 604 would join at the top ofthe thermal storage chamber 608 such that the collimated or otherwiseconcentrated beam would strike the interior of the porcelain absorberelement 202 (FIG. 2A) (or 403, FIG. 4). However the solar collectionmethod presented in this disclosure is not limited to this method ofgenerating the collimated or otherwise concentrated beam of solarradiation.

The beam is aimed at an interior cavity of a porcelain or other ceramicelement 202 possessing a high resilience to thermal stress. The generalshape of the heating element is shown in FIG. 2A, which illustrates avertical cross section of the heating element: the interior cavity ofthe heating element forms a cone or concave depression 202 (FIG. 2A) (or403, FIG. 4) with angled or arcing edges that meet at a point at thebottom of the heating element's interior cavity. The diameter of thecone or conical cavity 202 (FIG. 2A) (or 403, FIG. 4) is chosen to beequal to or greater than the diameter of the collimated or otherwiseconcentrated beam that focuses upon it 201 (FIG. 2A).

The arcing or angled edges (FIG. 2A and FIG. 3) of the interior of theheating element 202 (FIG. 2A) (or 403, FIG. 4) allow the solar radiationto be distributed across a substantial portion of the height of theheating element's interior surface, preventing the intense power of thecollimated or otherwise concentrated beam 201 from generatingunacceptable thermal stress in the heating element and/or differentialthermal stress across the heating element's mass. The angled walls taperacross the diameter of the collimated beam, thus collecting theelectromagnetic radiation from the beam across the height of the conicalor concave interior cavity 202 (FIG. 2A) (or 403, FIG. 4) of the heatingelement.

One material option for the makeup of the ceramic heating element isfully vitrified porcelain. This material's high melting point, relativeimpermeability, and overall strength make it a good choice as a point ofaccumulation and distribution of heat. Additionally, the material's lackof metallic content—particularly in oxide form—greatly lowers thepotential for unit-destructive corrosion on the heating element'sinterior and exterior surfaces. However, a dark oxide-rich glaze may beapplied to the surface of the heating element's interior cavity in orderto enhance absorption of the incident solar radiation 201, and to act asa heat sealant.

In one embodiment, the exterior portion of the heating element is placedin direct contact with the thermal storage medium 205, 609 (FIGS. 2A and6). In some embodiments, salt mixtures containing sodium sulfate orhydrates thereof, ammonium chloride, sodium chloride, magnesium sulfate,nitrate salts and nitrate salt mixtures such as solar salt can be usedas a thermal storage medium due to their high sensible and latent heatcapacity, low cost and high availability and their lack of apparentdegradation in thermal storage capacity after long exposures to highheat and thermal cycling. The salt or other thermal storage medium 205surrounds the cone of the heating element 202 (FIG. 2A) (or 403, FIG. 4)and can be held in a stainless steel or ceramic capsule 204 (FIG. 2A),404 (FIG. 4) or a capsule made of another corrosion and heat resilientmaterial. In order to increase the thermal conductivity of the heatstorage medium 205, 609 (FIGS. 2A and 6), in one embodiment it may besuffused with or poured over a metal mesh, such as one made fromaluminum. One possible configuration is shown in FIGS. 2-4, showing theheating element forming the cap 202, 403, 304 of a thermal storagecapsule. The heat is thus transferred directly from the heating elementto the thermal storage medium by conduction. When used with a phasechange material such as solar salt as the thermal storage medium, a gapof space 302 (FIG. 3 top view) can be left to allow for volume change inthe material. Optional small ventilation holes 303 (FIG. 3) or othershaped openings can be placed in the top of the heating element or inthe capsule, or optional pressure valves can be integrated, to allow forpressure buildup in the cell to dissipate.

In various embodiments, the heating element 202, 403 and thermal storagemedium 205 may form the lid of a capsule 204, 404 made of ceramic,stainless steel, high heat-capacity plastics or other appropriatematerial or materials for the purpose of providing insulation to thethermal storage medium 205, 609 and protection against corrosion by thethermal storage medium (FIGS. 2A and 4). The capsule may containsufficient empty space 302 to accommodate volume change in the phasechange thermal storage material. The entire capsule may in turn beencased in a refractory material 405 for added insulation (FIG. 4),and/or partially surrounded by a vacuum as in a Dewar tube 404. Invarious embodiments, stainless steel, ceramic or other tubing 402, 407can allow water or another working fluid to pass through the thermalstorage chamber formed by the thermal storage medium 205, 609 to allowit to act as a boiler or evaporator to power an engine or turbine 408,613 or for other uses (FIG. 4 and FIG. 6). In one embodiment, thethermal storage chamber is used as the evaporator in an organic Rankinecycle (FIG. 6), which may use a scroll compressor in reverse or agerotor motor as the expander element 613.

In order to make optimal use of the solar insolation throughout the day,the method described in this disclosure would optimally be used inconjunction with a solar tracking method, or with a method of producinga collimated beam of solar radiation with stationary orientation as thesun moves throughout the day as described in U.S. Pat. Nos. 4,183,612,4,124,017, 8,689,784, and International Application No.PCT/US2016/021753, which are all incorporated by reference in theirentirety. The method of collecting solar radiation described in thisdisclosure is not limited with respect to the method of producing thecollimated beam of solar radiation.

In one embodiment, the thermal storage chamber 205, 609 formed by thethermal storage medium 205, 609, can be stored underground or partiallyunderground to take advantage of the insulating qualities of thesurrounding earth. The ease of projecting and redirectingelectromagnetic radiation with lenses and mirrors makes this applicationparticularly feasible for residential use.

The heat captured in the thermal storage medium can be extracted for useby passing pipes or finned tubes 402, 407 containing a working fluidsuch as water or organic fluids such as R245fa through it. It may thusact as a boiler or evaporator FIG. 4, 609. For further insulation of thethermal storage chamber, the entire apparatus may be encased in arefractory material 405, 607 and/or surrounded by a partial vacuum 404.One possible embodiment using a refractory casing 405 and aevaporator/boiler setup is shown in FIG. 4. A more comprehensiveillustration of solar absorption device used in an organic Rankine cycleis illustrated in FIG. 6.

In another embodiment, the chamber holding the solar salt or otherthermal storage medium 205, 609 in contact with the heating element 202,403 may be surrounded by another chamber or chambers 701, 702, 703holding phase change materials with lower melting points than theinterior chamber (FIG. 7). These secondary chambers 702, 703 may also befilled with packed clay or other substances with low reactivity and highsensible heat capacity. In one embodiment shown in FIG. 7, severaladjacent secondary chambers 702, 703 are arrayed around the central heatcollection point and separated by a thermally conductive material suchas metal, and contain phase change materials with progressively lowermelting points the further they are from the central heat collectionpoint 701, so as to maximize the thermal storage chamber's energystorage capabilities (FIG. 7 shows one example with three chambers,though the concept could be extended to greater than 3 chambers).

Corrosion and heat resistant pipes or finned tubes 402, 407 made of amaterial such as stainless steel, extruded ceramic, or thermallyconductive plastics pass through the thermal storage medium 205, 609,and the working fluid passes through the pipes and absorbs thesurrounding heat (FIG. 4 and FIG. 6). A pipe or pipes or finned tubes402, 407 of a small diameter can be used to ensure rapid heat transferfrom the thermal storage medium to the working fluid. In one embodiment,the heating pipes could coil around the tip of the ceramic heatingelement's exterior surface 403. The working fluid can be pumped into thepipes 605, or, in one embodiment, can be fed through a simple gravityfeed. In various embodiments, a one-way valve mechanism 606 such as aTesla valvular conduit (U.S. Pat. No. 1,329,559) or check valve 606 canbe placed at the inlet to the thermal storage chamber to ensure the heattransfer fluid flows only towards the outlet. In various embodiments, atank 610 that stores the working fluid which passes into the heatcell/evaporator 609 or another heat storage or coolant material can beplaced in close proximity to the heat cell itself to allow any heat lostfrom the cell to be partially recaptured in the fluid of the tank (FIG.6). A condenser 611 could also be used before feeding the working fluidback into the tank feeding the pump or gravity feed after it is used bya turbine or engine 613 or heat exchanger 612, allowing the wholeassembly to act as a closed-loop Rankine cycle (FIG. 6).

UTILITY

The solar collector presented in this disclosure could be ideal forresidential applications due to the possible compactness of theresulting thermal storage chamber and the ability to use it inconjunction with solar focusers that do not have reflective surfaces,thus eliminating the physical risk to passersby and birds. The thermalstorage chamber could be used as a boiler or evaporator as describedabove to power home steam turbines or steam engine based generators, ororganic Rankine cycles, for example those using scroll compressors runin reverse as expanders, or gerotor motors, or to provide hot water andsteam heat or other heated fluids.

The thermal storage chamber could also be used to heat cooking stonesfor use as cook surfaces, or to heat ovens. One possible configurationof the heating element described in this disclosure could have itembedded in a ceramic cell that would itself act as a cooking surface,as shown in FIG. 5. The high specific heat of ceramic materials and ofthe thermal storage medium allow for the possibility that the cell couldbe used as a cook surface for long periods after the cell has beenremoved from the source of solar radiation.

Another useful application of the thermal storage chamber produced bythe heating element described in this disclosure is to generate steam orother hot gases for powering vortex tubes, which separate pressured gasinto hot and cold streams, which may be used for low-scale electricitygeneration using Peltier generators operating on the Seebeck effect(e.g., as in U.S. Pat. No. 8,134,066). For example, the cold 805 and hot803 ends of vortex tubes could be oriented towards the cold and hot endsof Peltier thermoelectric generator elements 804, in a looped series(FIG. 8). Such a power generation method, though fairly inefficient withcurrent thermoelectric materials, would be very low cost and present nomoving parts to maintain.

The foregoing examples or preferred embodiments are provided forillustration purpose and are not intended to limit the presentinvention. All patent or non-patent references are incorporated byreference in their entirety.

What is claimed is:
 1. A solar power collecting system, comprising: aFrenel lens having a focal point positioned near a top portion of a tubewith a reflective interior surface, wherein the top portion of the tubehas a tapered portion which tapers to an opening into which solarradiation is focused, wherein the tapered portion is bent such that itresembles a trumpet bell aimed into the rest of the tube; a thermalstorage medium contained within a thermal storage capsule; and a ceramicsolar heating element, forming a cap of the thermal storage capsule, theceramic heating element comprising: a top surface exterior to thethermal storage capsule and forming a generally conical or concavedepression having a solar radiation absorption surface; and a bottomsurface interior to the thermal storage capsule and forming a generallyconical protrusion on the bottom surface, wherein, when the solarradiation is directed at the depression, the ceramic solar heatingelement collects heat energy from the solar radiation striking the solarradiation absorption surface, and wherein said solar heating elementtransfers heat energy to the thermal storage medium through theprotrusion on the bottom surface which extends into the thermal storagemedium and which is in direct contact with or very near to the thermalstorage medium.
 2. The solar power collecting system of claim 1, whereinthe solar heating element is composed of vitrified porcelain.
 3. Thesolar power collecting system of claim 1, where the solar radiationabsorption surface is coated by a layer of oxide-rich glaze in order toenhance absorption of the solar radiation, and to act as a heat sealant.4. The solar power collecting system of claim 1, wherein the bottomsurface of the solar heating element is textured with a honeycombpattern.
 5. The solar power collecting system of claim 1, wherein thebottom surface of the solar heating element is embedded with nichromewires that protrude into the thermal storage medium, to increase thermaltransfer.
 6. The solar power collecting system of claim 1, wherein thethermal storage medium is separated into a plurality of chambers arrayedaround the central solar heating element, wherein each interior chamberis surrounded by a thermally conductive material, and wherein eachchamber holds a phase change material as the thermal storage medium. 7.The solar power collecting system of claim 6, wherein the phase changematerial in each successive chamber of the thermal storage medium has ahigher melting point than in the chamber exterior to it.
 8. The solarpower collecting system of claim 1, wherein the Fresnel lens is used inconjunction with a converging or diverging lens to form a beam of solarradiation as a collimated or otherwise concentrated beam.
 9. The solarpower collecting system of claim 1, wherein the thermal storage mediumis a 60-40 mixture of sodium nitrate and potassium nitrate.
 10. Thesolar power collecting system of claim 1, wherein the thermal storagemedium is sodium chloride.
 11. The solar power collecting system ofclaim 1, wherein the thermal storage medium is used as an evaporator fora Rankine cycle.